In situ hybridization assays and immunoassays, which can be targeted for the nucleic acids and antigens of pathogenic viruses and microorganisms, as well as for those of human cells, provide important diagnostic tools. The value of such assays increases, however, if one increases the amount of detectable signal generated by a given amount of target-bound probe molecules. An important limiting factor for signal intensity is the permeability of the targets to the probe molecules. In in situ assays done with target cells, the probe molecules must diffuse through the outer membrane of target cells and to locations in the cell where the target molecules reside. The ability of the probe molecules to permeate the cells in such a manner will affect the amount of signal generated.
Another potential means of increasing the signal is to have a signal enhancing compound present during the final measurement of signal in the assay.
The present inventions involve the discovery of compounds useful as permeation and signal enhancers in in situ hybridization assays and immunoassays.